Recently, organic compounds have attracted widespread attention from academic as well as industrial research groups for use in organic electronics (OE), such as for example in photodiodes, photoconductors, organic light emitting diodes (OLEDs), and organic photovoltaics (OPV).
In these applications organic compounds offer numerous advantages for intermediate and final products as well as for their fabrication. To name a few advantages only, organic compounds offer weight reduction, flexibility and ease of mass production, for example by using printing methods.
Furthermore, the introduction of substituents allows for easy modification of the organic compounds, thus permitting to fine-tune their properties to the requirements of the intended application.
Chen et al., J. Appl. Phys. 103, 103721 (2008), disclose cesium carbonate as a functional interlayer at the cathode interface for polymer photovoltaics devices.
KR-A-20090013388 discloses an organic light emitting device with an electron injection layer, which is formed on the light emitting layer and is made of metal salts doped electron transport material.
Xu et al., Materials Science and Engineering C 32 (2012) 685-691, disclose a inverted polymer solar cell which was fabricated with cesium carbonate modified indium tin oxide substrates as the electrode and molybdenum trioxide modified aluminum as the anode.
Wu et al., Appl. Phys. Lett. 88, 152104 (2006), discuss electronic structures and electron-injection mechanisms of cesium carbonate-incorporated cathode structures for organic light emitting devices.
Huang et al., Adv. Funct. Mater. 2007, 17, 1966-1973, disclose low-work-function surfaces formed by solution-processed and thermally deposited nanoscale layers of cesium carbonate.
Li et al., Appl. Phys. Lett. 88, 253503 (2006), disclose the effect of interfacial buffer layers—vanadium oxide (V2O5) and cesium carbonate (Cs2CO3)—on the performance of polymer solar cells.
US-A-2011/057920 discloses organic electroluminescence display devices, wherein the electron injection layer may contain at least one alkali metal and alkaline-earth metal.
However, the use in photodiodes poses very high requirements on the organic compounds in that the injection current from the electrodes under reverse bias is to be as small as possible, and in that impurities have to be avoided as much as possible, frequently necessitating the production of photodiodes in a clean room environment.
While much progress has been made, there is still room to improve the performance of organic compounds in certain applications and also to enlarge the pool of available compounds and compositions for certain applications. Additional advantages of the present invention will become evident from the following description and examples.